CWG3179 More edge cases for a void function parameter

tkoeppe · Jul 11, 2026 · Jun 18, 2026 · Jun 18, 2026 · Jun 18, 2026 · Jun 18, 2026
commit 991a3d690e2b62d4f12e1fa0154bc48084577162
diff --git a/source/declarations.tex b/source/declarations.tex
@@ -3822,13 +3822,30 @@
 If the
 \grammarterm{parameter-declaration-clause}
 is empty, the function takes no arguments.
-A parameter list consisting of a single unnamed non-object parameter of
-non-dependent type \keyword{void} is equivalent to an empty parameter
-list.
+A parameter list consisting of a single unnamed non-object parameter
+whose type is the same as\iref{temp.over.link} \keyword{void}
+is interpreted as an empty parameter list.
 \indextext{parameter!\idxcode{void}}%
 Except for this special case, a parameter shall not have type \cv{}~\keyword{void}.
 A parameter with volatile-qualified type is deprecated;
 see~\ref{depr.volatile.type}.
+\begin{example}
+\begin{codeblock}
+template<class T>
+struct S {
+  void f(std::void_t<T*>);      // \#1
+};
+S<int> x;                       // error: \#1 has a parameter of type \tcode{void}
+
+template<class T>
+struct S2 {
+  void f(std::void_t<int*>);    // \#2
+};
+S2<int> y;                      // OK, \#2 is a zero-parameter function
+\end{codeblock}
+\end{example}
+
+\pnum
 If the
 \grammarterm{parameter-declaration-clause}
 \indextext{argument type!unknown}%